Rotary cutters

ABSTRACT

The invention provides for means for mounting a rotary cutter so that the cutter is reclaimable or more easily reclaimable than hitherto known to the applicant. By this means the journal and load pin rotatably supporting the cutter is made in one. Furthermore there is provided in a saddle supporting the journal, an angular notch to restrain the journal against rotation. Still further, there is provided a saddle to support the journal, the saddle having a detachable limb having an angular notch to restrain the journal against rotation.

United States Patent 1 Venter [4511 Aug. 7, 1973 1 ROTARY CUTTERS [75]Inventor: Pieter Lawrence Venter,

Johannesburg, Transvaal Province, Republic of South Africa [73]Assignee: Paddy McDonnell (Proprietary) Limited, Johannesburg, TransvaalProvince, Republic of South Africa 2] Filed: Dec, 2 711- [21] PP No.:212,50

[30] Foreign Application Priority Data June 28, 1971 Republic of SouthAfrica...... 4204 [52] US. Cl 175/364, 175/353, 175/371, 175/374,175/347 [51] Int. Cl. E21c 13/00, E21c 23/00, 1521b 9/12 [58] Field ofSearch 175/334, 335, 357-361, 175/363, 364, 368, 344, 371, 372, 376, 53;

[56] References Cited UNITED STATES PATENTS 3,612,196 10/1971 Dixon175/364 2,187,037 1/1940 Kirkpatrick 3,054,466 9/1962 Wagnon et a1175/347 3,203,492 8/1965 Lichte 175/364 X 3,658,141 4/1972 Schumacher...175/364 1,812,681 6/1931 Brauer 175/371 X 3,216,513 11/1965 Robbins eta1... 175/372 X 3,545,811 12/1970 Montacle 299/86 X 3,601,207 8/1971Coski et a1 175/364 X 3,627,068 12/1971 Wagnon et a1... 175/347 X3,633,691 1/1972 Talbert 175/344 X Primary Ex ominer- Pavid l-l P rovvnA tiomeysiTie lvalle Goldsmith, ldester Horvvitz et a1.

51 ""Aismer Theinvention providesiar inanfir mounting rotary cutter sothat the cutter is reclaimable or more easily reclaimable than hithertoknown to the applicant. By this means the journal and load pin rotatablysupporting the cutter is made in one. Furthermore there is provided in asaddle supporting the journal, an angular notch to restrain the journalagainst rotation. Still further, there is provided a saddle to supportthe journal, the saddle having a detachable limb having an angular notchto restrain the journal against rotation.

4 Claims, 4 Drawing Figures SHEET 2 BF 2 FIGS. FICA.

ROTARY CUTTERS BACKGROUND TO THE INVENTION This invention relates toimprovements in or relating to rotary cutters. The invention relates inparticular to improved mountings for rotary cutters for drilling bigholes such as shafts, raises and tunnels.

Rotary cutters for drilling big holes as presently known to theapplicant are mounted for rotation about a tubular journal having a borein which a load pin is received. The load pin is removably mounted inapertures provided through one or more limbs of a supporting saddle. Inorder to prevent rotation of the journal, the, journal is provided witha shoulder engaging some portion of the saddle. The lug is well abovethe centre line of the journal bore.

To remove the cutter from the saddle the load pin has to be withdrawn inan axial direction from the journal and from the apertures in thesaddle. Since the cutter is mounted with very fine tolerances in thesaddle it often happens that due to minimal wear or shock loads abending movement is induced in the shoulder onthe tubular journalthereby causing fracture or deformation of the shoulder and/or thejournal. Due to the very fine tolerances, the fracture or deformationmakes it almost impossible to withdraw the load pin from the journal andfrom the apertures in the saddle when the cutter has to be removed. Dustparticles together with water often also cause the load pin to seize.This necessitates flame cutting the saddle and cutter to remove thecutter, removing the saddle and repairing it. This is a laborious, aswell as costly and wasteful operation as the cutter is always destroyed.

Furthermore, it often happens that the load pin works loose, whereby thecutter is forced out of the saddle and destroyed.

It is an object of the invention to mount a rotary cutter so as toovercome or at least to alleviate the above described difficulties.

According to the invention there is provided mounting means for mountinga rotary cutter having a bore, the mounting means including ajournal-cum-load pin receivable in the bore of the cutter and includingmeans to restrain the journal-cum-load pin against rotation.

The means to restrain the journal-cum-load pin against rotation maycomprises an angular formation such as a lug onthe journal adapted toseat in a complebe rotatably mounted and being further adapted torestrain the journal against rotation.

Further according to the invention there is provided mounting means formounting arotary cutter having a bore, the mounting means including asaddle having at 'least one detachable limb having an angular notch inwhich a journal is receivable for rotatably supporting the cutter.

The invention also extends to the combination of a rotary cutter andmounting means in accordance with the invention.

The invention still further extends to a drill bit for raise drillingwhich includes mounting means for a rotary cutter in accordance with theinvention.

In order to permit deformation of that part of the saddle in whichtheangular notch is provided, a slot may be provided leading out of thenotch into the saddle. The slot facilitates the clamping together of theopposed parts of the saddle defining the slot so that the lugs on thejournal may be-clamped in the notch.

There may conveniently be provided a wearing pad to line at least thatpart of the notch along which the lugs on the journal are supported. Thepad may be removable so as to be replaceable when worn. The wearing padis preferably of a softer material than the journal lugs to prevent thejournal from wearing, thus making the journal re-usable.

The wearing pad may be located in the notch in the saddle by providing aplurality of holes through the pad and by filling the holes with weldingextending to the surface of the saddle. Any welding projecting from theholes is filed away or machined away flush with the surface of the pad.

The invention is now described by way of examples with reference to theaccompanying drawings, in which z r FIG. I shows diagrammatically a planview of a raise boring bit;

FIG. 2 shows an exploded view of a saddle and rotary cutter suitable foruse in positions 3 to 8 of the bit shown in FIG. 1 or in positions offurther bolt-on stages, or in larger boring heads such as tunnel boringheads;

FIG. 3 shows a side view of a rotary cutter and saddle suitable for usein positions 1 and 2 of the bit shown in FIG. I; and

FIG. 4 shows an end view of the cutter and saddle shown in FIG. 3.

Referring to FIG. 1, reference numeral 10 indicates generally a raiseboring bit having a platform 12 and a stem 14. Rotarycutters marked 1 to8 are mounted on the platform I 2. Although the drawing shows only eightcutters, a lesser or greater number of cutters may be mounted on theplatfonn, or on an additional bolt-on stage. I

Referring to FIG. 2, reference numeral 16 indicates a saddle in which tomount a rotary cutter 18. The cutter 18 is offrusto-conical shape andmay forinstance be any one ofthe cutters 3 to 8'shown inthe raise boringbit illustrated in FIG. 1. Along the periphery of the cutter 18 theremay be provided cutting inserts 20.

Thecutter 18 is rotatably mounted on a journal 22 via roller bearings 21and 23. The endsof the journal 22 terminate in rectangular lugs 24 and26 through which are provided bolt holes 28 and 30. Screw threads 32 areprovided on one end of the pin to receive a locking nut (not shown). Thecutter 18 :is axially located-on the bearings 21 and 23 between thislocking nut and an annular shoulder 34 on the other end of the journal.

The saddle 16 has two limbs 36 and 38 in which there are providedrectangular notches 40 and 42 respectively. The notches are forreceiving thelugs 24 and 26 and for locating the journal 22 againstrotation. Bolt holes 44 and 46 extend through the limbs 36 and 38 forreceiving locking bolts 48 and 50. The locking bolts extending throughthe holes 44 and 28 and through the holes 46 and 30 lock the lugs 24 and26 to the saddle l6.

The base of each notch 40, 42 is lined with a replaceable wearing pad52, 54 on which the lugs 24, 26 are seated. The wearing pads are securedby providing holes 55 through them which are filled in with weldingextending to the notch surface. Excess welding is filed away or machinedaway.

Slots 56, 58 extend from the notches 40, 42 into the limbs 36, 38. Theslots permit deformation of the limbs 36, 38 and thus facilitate theclamping of the lugs 24, 26 in the notches 40, 42.

In use, the load is transmitted from the rock face via the rotary cutter18, the bearings 21, 23, the journal 22, the lugs 24, 26 and the wearingpads 52, 54 to the saddle 16. Thus the load is transmitted from thejournal to the saddle well below the centre line of the journal, therebyeliminating the possibility of a bending movement being induced as inthe arrangement of the prior art.

In order to remove the cutter l8 and journal 22 from the saddle 16, thelocking bolts 48, 50 are loosened and are withdrawn from the holes 44,28 and 46, 30. The journal 22 may now be lifted out of the notches 40,42. By unscrewing the locking nut (not shown) from the threads 32 thejournal 22 may be withdrawn from the bore of the cutter 18.

The advantage of the notches 40, 42 in the saddle l6 is-that the journal22 can be lifted out of the saddle. It is not necessary to withdraw thejournal in an axial direction from the saddle. Reclamation of the cutter18 is thus considerably facilitated over the known method of having towithdraw the pin in an axial direction from the saddle.

Referring to FIGS. 3 and 4, there is shown a rotary cutter 60 and itsassociated mounting for use in the positions l and 2 in the boring bitshown in FIG. 1. The cutter 60 is rotatably mounted via roller bearings62 and 64 on a journal 66. The cutter is axially retained in position onthe journal 66 between a lockingnut 68 which is screwed onto thejournal, and an annular shoulder 70 on the journal. The end 72 of thejournal 66 is journalled in a bearing 74 in the boring stem 14, thisjournal end being hard-chromed to resist wear. The outer end 76 of thejournal 66 is of an angular shape similar to the lug 24 in FIG. 2.

The lug 76 is receivable in a notch 78 in a support 80. Bolt holes areprovided through the support 80 and the lug 76 for receiving a lockingbolt 82 for clamping the lug 76 in the notch 78. A wearing pad 84 and aslot 86 similar respectively to the wearing pads 52, 54 and the slots56, 58 in FIG. 2, are provided in the support 80.

A flange 88 is provided at the base of the support 80 to seat on acomplementary flange 90 fast with the platform 12. Bolt holes areprovided through the flanges 88 and 90 for receiving clamping bolts orcap screws 92 for clamping the flanges to one another. The flange 90 isso positioned that the level of its top face is below the periphery ofthe cutter 60 to permit the cutter to pass with clearance over theflange 90 when the cutter is removed.

When it is desired to remove the cutter 60 from the journal 66, thebolts or cap screws 92 are unscrewed and removed to free the flanges 88and 90 from one another. The whole cutter and journal assembly is nowslid in an axial direction out of the bearing 74. The bolt 82 is removedand the lug 76 removed from the support 80. By unscrewing the lockingnut 68, the cutter 60 may be withdrawn axially from the journal 66.

The advantage of the mounting arrangement shown in FIGS. 3 and 4 is justas in the case of the mounting arrangement illustrated in FIG. 2 thatreclamation of the cutter 60 is facilitated. In order to remove thecutter from the stem 14 it is not necessary to withdraw the journal 66axially from the cutter. Instead the procedure is followed as alreadydescribed above. Costly lug removal from the bit body for repairs as isnecessary in the prior art arrangement is thus eliminated.

A further advantage of the invention is that by providing a combinedjournal-cum-load pin, the separate tubular journal is eliminated andwith it the difflcultie's in and problems caused by the known methodsofrestraining the tubular journal against rotation.

A still further advantage of the invention is that the angular lugs andassociated notches in the saddle lock the journal positively againstrotation.

I claim:

1. Mounting means for mounting a rotary cutter having a bore, themounting means including a saddle having at least one limb in which isprovided an angular notch in which is receivable an end of a journal onwhich the cutter may be rotatably mounted the end of the journal beingof a complementary angular crosssection so that the journal isrestrained against rotation, aligned apertures being provided throughthe saddle and the angular journal end to receive a tie-bolt forclamping the angular journal end in the notch, there being provided aslot in the saddle limb having the notch and leading out of the notch topermit deformation of the saddle limb having the notch during clampingof the angular journal end in the notch.

2. Mounting means according to claim 1 in which the notch is rectangularin cross-section and in which the mounting means includes a flat wearingpad to line at least that part of the notch along which-the journal issupported.

3. Mounting means according to claim 1, in which the saddle has twolimbs each limb being provided with an angular notch in which to receivea journal end having a complementary cross-section.

4. Mounting means for mounting a rotary cutter having a bore, themounting means including a saddle having at least one detachable limbhaving an angular notch in which an end of a journal is'receivable forrotatably mounting the cutter, the end of the journal being of acomplementary angular cross-section so that the journal is restrainedagainst rotation, aligned apertures being provided through the saddleand the angular journal end to receive a tie-bolt for clamping theangular journal end in the notch, there being provided a slot in thesaddle limb having the notch and leading out of the notch to permitdeformation of the saddle limb having the notch during clamping of theangular journal end in the notch.

t t t i i

1. Mounting means for mounting a rotary cutter having a bore, the mounting means including a saddle having at least one limb in which is provided an angular notch in which is receivable an end of a journal on which the cutter may be rotatably mounted the end of the journal being of a complementary angular cross-section so that the journal is restrained against rotation, aligned apertures being provided through the saddle and the angular journal end to receive a tie-bolt for clamping the angular journal end in the notch, there being provided a slot in the saddle limb having the notch and leading out of the notch to permit deformation of the saddle limb having the notch during clamping of the angular journal end in the notch.
 2. Mounting means according to claim 1 in which the notch is rectangular in cross-section and in which the mounting means includes a flat wearing pad to line at least that part of the notch along which the journal is supported.
 3. Mounting means according to claim 1, in which the saddle has two limbs each limb being provided with an angular notch in which to receive a journal end having a complementary cross-section.
 4. Mounting means for mounting a rotary cutter having a bore, the mounting means including a saddle having at least one detachable limb having an angular notch in which an end of a journal is receivable for rotatably mounting the cutter, the end of the journal being of a complementary angular cross-section so that the journal is restrained against rotation, aligned apertures being provided through the saddle and the angular journal end to receive a tie-bolt for clamping the angular journal end in the notch, there being provided a slot in the saddle limb having the notch and leading out of the notch to permit deformation of the saddle limb having the notch during clamping of the angular journal end in the notch. 